DE102009017051A1 - Process for recovering pulp from lignocellulosic biomass - Google Patents

Abstract

Disclosed is a process for the recovery of pulp by separating lignin from a lignocellulosic biomass in the form of plants or plant parts, wherein the lignocellulosic biomass in an alkaline medium containing alkanolamine, digested in a digester and dissolved lignin of the obtained raw pulp is separated. This process is characterized in that the lignocellulosic biomass is not derived from wood and is digested at a temperature of less than about 170 ° C in an alkanolamine and water based disintegrant in which the weight ratio of alkanolamine to water is 80:20 is set to 20: 80, and resulting raw pulp is separated from the spent liquor by conventional methods. Of particular advantage is this process for the production of pulp from annual plants, in particular wheat straw. The process is favored by carrying out the digestion in the presence of a catalyst, in particular anthraquinone. It may be followed by an advantageous bleaching. This process is characterized by great economy, in particular due to the high recovery rates of the alkanolamines used, and leads to lower environmental impact of wastewater and reduced disposal costs. The process design leads to a high yield of pulp and largely excluded degradation of alkanolamine, in particular ...

Description

The The invention relates to a process for the production of pulp Separating lignin from a lignocellulosic biomass, in particular straw and other fiber-supplying non-woody plants, wherein the lignocellulosic biomass is in an alkaline medium, contains the alkanolamine, digested in a digester and dissolved lignin and low molecular weight carbohydrates are separated from the obtained raw pulp.

While The last 30 years is the worldwide production of pulp from biomass other than wood constantly increased. Of the Proportion of fiber materials that do not rely on wood as the starting material decline is nearly 12% worldwide. wheat is cultivated on all continents, so that its straw is used for the production of Pulp could be used extensively. According to the statistics FAO of the United Nations (from 2007) the world production of wheat 600 million tons. 15 million Tons of it were produced in Iran alone. About half of the resulting wheat straw is used in farms. The other Half is either burned or plowed into the ground. Based on these data, it can be concluded that the amount of wheat straw, which is available for pulp production, for the production 100 million tons of pulp per year are used could. In fact, only 4.5 million wheat straw pulp produced. The digestion with caustic soda is a prevalent one Process for the production of pulp from annual plants. This shows serious disadvantages. Dissolve strongly alkaline digestion liquors carbohydrates to a significant extent, resulting in the yield affected by pulp. Most annual plants have a high content of silicates that are in the highly alkaline Digestion solutions solved to a considerable extent causing serious problems in the evaporation plants and the recovery boilers leads. These are the main reasons why the handling leaching the soda process and recovering the digestion chemicals continue to be problematic.

Theoretically may be organic solvents alone or in Mixing with water overcomes the problems of chemical recovery, those with conventional pulp production from annual plants are connected. In particular, low-boiling alcohols or organic acids easily recovered by distillation and returned to a subsequent cooking process become. Dissolved organic material can either be added to Energy production burned or fed to various applications be used for alcohol or yeast production or as a chemical raw material. However, so far no commercial pulp process is used organic solvents.

Monoethanolamine (MEA) has long been recognized as a very selective delignifying agent and for isolating holocellulose and determining its content in wood (cf. Harlow, WM, Wise, LE, Am. J. Botany 25 (1938): pp. 217-219 ). Thereafter, various studies have been conducted on the use of MEA for the production of pulp. Mainly this research concerns the use of wood as raw material. MEA was used in alkaline pulping to aid in the delignification process. Extensive studies on the use of MEA as the sole delignifying agent in hardwood (Eucalyptus grandis) and coniferous (Pinus elliotti) cooking were carried out by Wallis (cf. Wallis, Cellulose Chemistry and Technology, 10 (3) (1976), pp. 345-355 ). The assumed reactions that occur during the MEA delignification of wood are described in the literature (loc. Cit.).

The outstanding characteristics of pulp production with MEA is the exceptionally good protection of hemicelluloses, resulting in an unusual high yield of pulp leads. On the other hand, that is maximum degree of delignification, with MEA as the sole delignifying agent is limited, especially in the case of softwood. Therefore must use sharp cooking conditions, especially high temperatures be sufficient to delignify in the production to obtain a pulp suitable for bleaching. In this regard, It must be remembered that MEA decomposes at a boiling point of about 171 °. Therefore, the temperature of about 171 ° C should biomass digestion underrun to avoid excessive loss of MEA. Furthermore, it should be noted that MEA in reactions with lignin and therefore the MEA losses are high, if the raw material used for pulp production has a high content of lignin, which is difficult due to its structure is to be reduced.

Based on these facts, it can be concluded that MEA should not be used for pulpwood pulp production. MEA can generally be used for pulp production from hardwood. It seems doubtful that this is a practically valuable alternative as the temperatures to be applied must be high. Even small losses of MEA make this process over conventional kraft pulp processes with their very effective recovery system for inorganic cooking chemicals not competitive.

The Situation is completely different when annual plants, like wheat straw, as a raw material for the production of pulp used in the soda production process. Because of the problem, that with the high silicate content in alkaline digestion liquors most plants have straw pulp production no chemical recovery system. AND ALL Sodium hydroxide, which is used in the digestion, must be supplemented become. In addition, wheat straw has a low lignin content, can be easily digested under mild conditions and requires For dissolution of lignin a relatively small batch Chemicals. The big advantage of the digestion of annual plants with MEA is in direct distillative recovery from MEA. After the distillation of MEA, the remaining organic Material either as chemical raw material or as nitrogen-containing organic fertilizer are used, in contrast to mineral nitrogen fertilizer acts long-term, since Nitrogen by microbial degradation of the carrier material is gradually released.

In order to complete the relevant prior art described above, the following patent literature should be discussed: US-A-4 597 830 deals with the digestion of lignocellulose in an aqueous solution containing a catalyst, such as anthraquinone, using an alcohol / amine mixture to promote digestion of the lignocellulose. The US-A-4,178,861 also describes the digestion of lignocellulose-containing materials and proposes the use of, inter alia, anhydrous monoethanolamine with simultaneous addition of catalysts, such as anthraquinone. The EP-B-0 149 753 deals with the decomposition of wood under heat and pressure by impregnation and boiling of chips or shavings in an aqueous digestion solution containing a short-chain alkanolamine, such as monoethanolamine, in addition to ammonium hydroxide as a catalyst. The DE-A-26 40 027 relates to a further development of the classical soda-digestion process, whereby among other things anthraquinone is used.

The The above statements on the prior art show that Here are many tasks of improvement. This also applies to digestion processes in which alkanolamines, especially monoethanolamine, are used. That's the loss consumed alkanolamine in the digestion procedures described very high and the achievable delignification-limited. It would be desirable, high-availability cereal straw, in particular wheat straw, economically with alkanolamine to pulp process and thereby a degradation of the pulp and a decomposition exclude alkanolamine during digestion or at least reduce. Would be desirable it also largely recovers the alkanolamine from the process and to recycle the process. In development of such desirable technical proposal should be additional to connect an environmentally friendly bleach of the pulp so that the overall process of pulp production technological and economic needs of a modern pulp manufacturing process can be adjusted. The present invention is therefore the Task based, the claims listed above to fulfill.

The Solution to the problem addressed here, of which the Present invention proceeds, turns in a development of the above-described prior art in that the lignocellulosic biomass does not go back to wood and at a temperature of less than about 170 ° C in a digestor based on alkanolamine and water in which the weight ratio of alkanolamine increases Water is set to 80:20 to 20:80, and resulting raw pulp is separated from the waste liquor by conventional methods.

The essence of the invention is therefore that not any lignocellulosic biomass can be used for the designated method, but it is limited in particular to straw and other fibers supplying non-woody plants. In addition, it has surprisingly been found that alkanolamine in admixture with water while maintaining a specific. Weight ratio of alkanolamine to water as a digestion agent is particularly suitable, and in addition the limitation of the maximum temperature in the process has to be considered. The use of the digestion agent alkanolamine / water produces surprising advantages, which will be discussed in detail later. First, the invention-relevant features and preferred embodiments of the invention are shown in more detail:
The method according to the invention is expressly directed to lignin and other accompanying substances, including hemicelluloses (polyoses), being separated as far as possible from the pulp. The term lignocellulosic biomass, as shown above, is subject to a relevant limitation in that the lignocellulosic biomass should not be due to wood, since thus the desired Abtren lignin is not possible under advantageous conditions to any appreciable extent. Therefore come within the scope of the invention, in particular plants and plant parts of annual plants, in particular straw of cereals such as wheat, barley, oats, rye, corn and rice, and dried grasses, reeds, sugar cane bagasse and bamboo in question. Among the above-mentioned annual plants, wheat straw is particularly preferable. These annual plants usually have a comparatively high silicate content, which may be significant for the success of the invention, without being construed as limiting. In principle, it is possible to use such biomasses, which are comparable in their chemical and morphological composition with the materials derived from annual plants. It should be noted here that the processing of wood to pulp is solved in the prior art, wherein the sulfate process is particularly economical.

In The rule is the biomass before it is the inventive Process is fed, sufficiently comminuted, for example by shredding and in individual cases also by further crushing. Also, it may be appropriate be to dry the biomass before the start of the process, with one to extensive drying does not make sense, since the amount of water, the the biomass in the process of the invention and those included in the digestion system is, the above-mentioned conditions of the relationship Alkanolamine must comply with water.

in principle it is possible to use the biomass before it becomes the invention Method is supplied, according to known methods of Pre-treat prior art, for example, a preceding Softening of the fiber composite to achieve. So this could be be done by the starting material of a known steam or ammonia treatment. However, it has been shown that As a rule, such measures do not offer any advantages.

In terms of of the term alkanolamine, the invention is not subject to any relevant Restrictions. It is preferred that as alkanolamine a short-chain alkanolamine, in particular an alkanolamine with 1 up to 8 carbon atoms, in particular 1 to 4 carbon atoms, is used. Among these alkanolamines are monoethanolamine, Monopropanolamine, monobutanolamine and / or diglycolamine, in particular Monoethanolamine, to be regarded as preferred. The disintegrating agent monoethanolamine (MEA) / Water has several benefits. In the digestion MEA protects the cellulose from degradation and preserves also the hemicelluloses. At the same time it is delignifying. In the digestion of the lignocellulosic biomass or in The extraction of lignin may be an advantage, in addition to use another solvent for lignin, in particular with swelling action for the cellulose and hemicellulose.

The Framework conditions, the ratio of alkanolamine to water are to be adhered to are fixed at 80:20 to 20:80. Prefers It is when the ratio alkanolamine to water at 70:30 is set to 30:70, in particular 60:40 to 40:60. All it is particularly preferred if the ratio of alkanolamine to water 53 to 57 to 57 to 53. The hereby The amount of water involved, as already stated, not only on the water content of the mixture alkanol / water, the represents the digestion agent in the digester or used autoclave, but also on the proportion of water passing through the more or less moist biomass is added to the digestion system. So could One can specify as a preferred rule that a biomass to high water content expediently by drying to a water content is adjusted from about 10 to 30%, in particular about 15 to 25%. Further drainage would be with a larger one Energy consumption and would provide no benefit.

For the invention it is very important that in the process management for obtaining pulp from the biomass within the digester or autoclave in which the mentioned digestion agent Alkanolamine and water is the temperature of about 170 ° C is not exceeded. It was found by the inventors that exceeding this temperature to a degradation and loss of alkanolamine used, in particular monoethanolamine, would lead. On the other hand could be higher Temperatures lead to an undesirable pulping. Therefore, it is particularly advantageous, the temperature at the conclusion less than about 165 ° C, especially less than 150 ° C adjust. As the preferred lowest temperature of the digestion indicate about 120 ° C, especially about 140 ° C. The temperature range from 140 to 160 ° C is considered special preferred, since hereby the above formulated object of the invention is solved particularly advantageous.

at the implementation of the invention Procedure usually arises due to the chemicals introduced an alkaline medium. As a result, the pH is above 7, especially at more than 10 and also at about 12. This works from the examples below.

in principle is it possible to repeat the procedure described above, a further delignification and a purer pulp product to obtain. Here additionally known measures used in the prior art.

To the digestion stage carried out according to the invention becomes the cellulose raw material (cellulose / Hemicellulose) in usual Won way. So can the strong dark brown to black colored waste liquors from the pulp fibers be separated in a professional manner, for example, according to the usual for solid / liquid separation Process, in particular by filtration, pressing or by Centrifuge.

Of the Digestion of the lignocellulosic biomass is preferably carried out within a period of 15 minutes to 4 hours, in particular of 1 until 3 h, counting from the end of the heating up. Especially preferred is a period of 2 to 3 hours. To optimize the invention Procedure, it is appropriate to the liquor ratio of lignocellulosic biomass to be digested (Dry matter) and digestion mixture alkanolamine / water advantageous in particular to about 8: 1 to 2: 1, the range from about 5: 1 to 3: 1 is particularly preferred.

After all is the digestion of the lignocellulosic biomass or the Extraction of lignin in the presence of suitable catalysts accelerated. These are in particular catalytically active quinones, especially in the form of naphthoquinone, anthraquinone, anthrone, phenanthrenequinone. anthraquinone has proved to be particularly advantageous, but also alkyl-substituted Derivatives thereof, such as 2-methylanthraquinone, 2-ethylanthraquinone, 2,6-dimethylanthraquinone, 2,7-dimethylanthraquinone and the like. Final reactions are promoted in the presence of the catalyst and side reactions strongly pushed back. moreover Advantageously, low kappa numbers are obtained.

The inventive method can be both continuously and batchwise. In a batch mode z. As the crushed lignocellulose-containing Biomass with the water still contained therein, in particular in an autoclave, with the digesting agent alkanol / water and optionally and preferably added to one of the designated catalysts. The described mandatory features of the invention are To comply with the procedure. The continuous digestion is preferably carried out by filling in a reactor Lignocellulosic biomass from optionally preheated Flow through the digestive or the zu extracting or digesting lignocellulose-containing Biomass leads to the digestion agent in countercurrent. Here shows up against the batch mode, ie the stationary one Operation, the advantage that due to the removal of the degradation products with the digestion agent side reactions are largely excluded. In addition, with the same digestion effect with a lower liquor ratio from digestion to lignocellulosic biomass and also be worked at a lower temperature. In another preferred Embodiment, the digestion is multi-stage, d. H. in at least two successive outcrops or Extractions performed with the respective mixture alkanolamine / water.

The process according to the invention can be advantageously carried out by obtaining the liginin-containing liquid phase which has been obtained after separation of the raw pulp or after separation of the delignified and / or bleached pulp, in particular by centrifuging, pressing or filtering and washing, and in addition to lignin and Carbohydrates further biomass extractives, and optionally containing the mentioned catalyst, treated as follows: The waste liquor is evaporated in a thin film evaporator, film evaporator or tube evaporator, wherein alkanolamine and water are separated. The distillation residue is fed to a further utilization for energy production, as a chemical raw material or as an N-deposit fertilizer, the latter utilization can also be carried out with additives. In order to obtain a pulp with higher purity and also with a low lignin content, it is preferred that the raw pulp be bleached after removal of the waste liquor and optionally additional washing. It is expedient to make the bleaching so that this is carried out in the context of an alkanolamine / oxygen stage (with alkanolamine as alkali source) for further delignification and then the bleached pulp of adhering liquid portions in which alkanolamine is still contained, especially pressed and filtered to obtain thereon an alkanolamine-enriched liquid phase, which is returned as a filtrate to the digester, optionally with intervening measures such as washing the raw pulp. In order to further enrich the liquid phase of alkanolamine, evaporation can be carried out with low thermal stress, as already mentioned above, which is carried out in particular in a thin film evaporator, falling film evaporator or tubular evaporator. It is particularly preferred that the filtrate obtained after the measure of bleaching by, for example, pressing off recovered pulp, which, inter alia, also contains alkanolamine, in particular MEA, as a wash solution for washing the separated from the spent liquor of the digester raw pulp is used. In principle, it may be expedient to subject the pulp obtained after bleaching with the alkanolamine / oxygen stage to further bleaching in customary ECF and TCF sequences, especially under the action of oxygen / and hydrogen peroxide, hydrogen peroxide in the presence of NaOH, O ₃ , ClO ₂ or formamidinesulfinic acid (FAS).

The above-described inventive approach after seizure of the raw pulp or the pure pulp will be described in more detail below:
It has thus been found that the pulp (cellulose / hemicellulose mixture) obtained according to the invention or obtained after delignification and / or bleaching does not become valuable products in all desirable secondary reactions, in particular because of the adhering alkanolamine, such as in particular for the pyrolytic production of wood gas for the production of fuel , suitable is. It is advisable to treat the raw pulp or cellulose to separate the still adhering alkanolamine a) with a nonaqueous solvent dissolving the alkanolamine and to separate the alkanolamine-containing nonaqueous solvent and / or b) the raw pulp / pulp with an alkanolamine to treat insoluble solvent, the treatment is carried out both before and after the separation of the solution of lignin and from the resulting two-phase mixture, the alkanolamine phase is separated. In measure a) the separated alkanolamine-containing solvent mixture is separated by distillation to recycle the alkanolamine in the process. It is preferred here that by adding the alkanolamine-dissolving non-aqueous solvent towards the end of the distillation residual alkanolamine. Azeotrope is separated. The non-aqueous solvent used is preferably ethanol, methanol, DMF, toluene and / or acetone or an alkanolamine solvent. Preferably, the solvent-moist pulp obtained according to measure a) is reacted directly in a pyrolysis process to form a gas mixture suitable for the production of fuel.

at the described measure b) is preferably done, that the alkanolamine does not dissolve the solvent an alkane, especially petroleum ether, pentane, hexane, alkane, diesel and / or biodiesel, or a non-alkanolamine dissolving Solvent is. Preferably, after the measure b) obtained two-phase mixture (after separation of the raw pulp) separated and the resulting alkanolamine fraction subsequently separated by distillation.

By the measures described above will be the alkanolamine in the Insofar as the invention largely isolated, then it expediently return to the beginning of the procedure. In addition, remaining Remains of lignin removed or processes with quantified lignin fed together with hemicelluloses (polyoses). in principle can between the extraction of the raw pulp and the Pulp still included expert action become.

The preferred measures according to which the lignin is separated from the various waste liquors are to be shown more specifically below: Thus, water and the alkanolamine used are separated off by distillation, preferably by vacuum distillation. Other separation processes that lead to the desired concentration of lignin extract (in the limit to dry matter), are suitable. Separation of the lignin also succeeds by adding a non-solvent to the solution of lignin in alkanolamine. The lignin precipitates in the form of solid particles and can be separated from the alkanolamine by a suitable solid / liquid separation process, such as filtration, centrifugation, thin-layer evaporation or membrane. The separation of the lignin can z. B. by introducing carbon dioxide in the diluted with water or better with the washing after the alkanolamine extraction, optionally concentrated lignin / alkanolamine extract. By concentrating by means of a thin film evaporation or other suitable distillation means, much of the alkanolamine is recovered in pure form and can be recycled to the process. The remainder of the alkanolamine is distilled after the water has been distilled off from the precipitating liquid after separation of the lignin, likewise in vacuo. The precipitation of lignin is thus achieved by introducing carbon dioxide and centrifuging. The addition compound alkanolamine which forms with the carbon dioxide can again be completely decomposed thermally or by injection of steam into alkanolamine and carbon dioxide. The residue consists of a degraded, reactive lignin. This can be supplied as a chemical raw material diverse applications, eg. As the production of thermosets of polyurethanes or binders. Accordingly, falls through the above-described measures a) and b), in particular in its advantageous embodiments, a lignin-containing, water or solvent-rich fraction, which can be used multiple times, the lignin is concentrated and a strong lignin containing and alkanolamine-rich fraction is obtained. From the alkanolamine-rich and low-water fraction, only a small amount of water needs to be distilled off, in order then, for example by a thin-film evaporation, to produce the largest amount of alkano to be able to recover lamin.

The Advantages achieved with the present invention are obvious. All introduced into the reaction mechanisms Connections are either largely recovered, such as the alkanolamine contained in the disintegrating agent, or Uses that are useful after economical workup fed. In particular, this applies to the lignin and the carbohydrates dissolved in the digestion. The pulp obtained according to the invention shows a surprisingly high purity and exceptional favorable reactivity. He has a favorable Kappa number less than 20, sometimes less than 15, on. The resulting pulp can be used to advantage for the production of paper pulp. and chemical pulp as well as for energy production (bioethanol) be used.

in the In view of the fact that the digestion agent is a mixture of alkanolamine and water with high water content is used, is the consumption strongly reduced to alkanolamine. As a digestion with a digesting agent Alkanolamine / water in a ratio of about 50:50 proceeds in an advantageous manner, in particular when the catalyst is added, can to a considerable extent alkanolamine, especially monoethanolamine, be saved, resulting in a significant increase in profitability leads. The alkanolamine has the advantage of recovery in a simple vacuum distillation. The invention allows the Digestion or extraction at a favorable liquor ratio (about 8: 1 to 2: 1), especially in continuous operation. This has a positive effect on the steam consumption during digestion in comparison to classical digestion method.

The inventive method can with slight modifications be integrated into existing facilities, with only Investment costs for an additional distillation unit attack. For new plants is the time-consuming chemical recovery replaced by a simpler and cheaper distillation. According to the invention, the lignocellulose-containing Biomass to a pulp with particularly favorable reactivity be further processed. This can be done in expert For example, converted to sugars and these to bioethanol be fermented. The resulting after the separation of lignin Alkanolamine has more value and can the inventive Procedures are fed back. After all there is the possibility of the raw pulp (even after the Prior art) in celluloses and hemicelluloses to separate and in this way to obtain a chemical pulp. Particularly preferred the use of the product obtained according to the invention Product, optionally after alkanolamine recovery, especially monoethanolamine recovery, as paper, Energy and chemical raw material or as N-Depot fertilizer.

As already stated, are with the monoethanolamine in the frame the invention achieves particular advantages. Complementary still to note the following: It arises for each used monoalkanolamine, in particular monoethanolamine, a very high recovery rate, which is of great economic Importance is, especially in view of the high costs of monoethanolamine with about EUR 1,400, - / t. A profitable process is possible using the alkanolamine in the invention by: mild conditions, as in the digestion a comparatively low temperature can be selected so that MEA is not is decomposed (boiling point 170 ° C), and less use of monoalkanolamine, especially MEA, by dilution with water, preferably in the ratio of about 1: 1 (Note: Due to the mild conditions of dilution the method is preferably limited to annual plants. With Wood should have chosen harsher conditions which lead to the decomposition of MEA).

The Invention will be described in more detail below by way of examples which should also be shown Individual parameters for the invention of particular relevance are:

Examples

at The experiments described below were for all Digestions wheat straw from the harvest of 2008 of an agricultural Operation in Schleswig-Holstein. The straw was in a shredder crushed, the fine material separated and in this form for the digestions in a 15 l rotary autoclave with external Shell heating and a process control system used. The Straw had a solids content of 90.3%. For all cooking were used uniformly 400 g of dry straw. The heating time to a maximum temperature was at all outcrops 60 min.

example 1

In the overall process is used as the alkanolamine monoethanolamine (MEA). From the follow From the overall consideration, it is apparent that here it is an essential aspect that the monoethanolamine is used in a mixture with water as a disintegrating agent and is recycled to the system after the raw pulp or cellulose has been recovered. In detail, the procedure is as follows, reference being made to the attached flow diagram ( 1 ).

A plant for carrying out the method according to the invention comprises a cooker according to a preferred embodiment 2 , a separator 8th , a delignification unit 10 and a bleaching unit 13 , Furthermore, the plant comprises a distillation device 11 , a water tank 5 and an MEA container 4 , The individual components of the system are coupled together by cables. The arrangement and connection of the individual components with one another is explained in more detail in the following process description:
The cooker 2 has a biomass feed 1 and a catalyst feed 3 on, causing the cooker 2 Biomass and catalyst is fed. The biomass preferably comprises wheat straw as a one-year-old plant. The cooker 2 Further, monoethanolamine (MEA) is replaced by a first MEA recycle 42 and water via a cooker supply line 5.4 fed. The biomass is in the digester 2 digested with a digestion solution of MEA and water in the presence of the catalyst. Preferably, the digestion is carried out at a boiling temperature between 130 ° C and 170 ° C, in particular between 140 ° C and 160 ° C, in particular at about 150 ° C. The digestion time is preferably 130 minutes to 170 minutes, in particular 140 minutes to 160 minutes, especially about 150 minutes.

Biomass digestion will be described below using a biomass digestion line 6.1 the separator 8th fed. The separator 8th is also via a first water pipe 5.1 Water from the water tank 5 fed. In the separator 8th a gradual separation of the pulp from the biomass digestion takes place. That over the first water pipe 5.1 supplied water is used as washing water. In the separation of the pulp waste liquor accumulates, which are the dissolved biomass and the digester 2 supplied digestion chemicals, in particular MEA comprises. The waste liquor is removed from the separator 8th via a leaching discharge 7.1 the distillation device 11 supplied, whose operation will be discussed later.

The one in the separator 8th separated raw pulp is via a pulp forwarding 6.2 the delignification unit 10 fed. The delignification unit 10 further includes an oxygen supply line 10.1 and an MEA feed in the form of a second MEA recycle 4.3 , About the second MEA feedback 4.3 becomes the delignification process in the delignification unit 10 MEA from the MEA container 4 fed. Further, the delignification unit 10 through a second water pipe 5.2 with the water tank 5 connected, so that the delignification process water can be supplied. In the delignification unit 10 For example, a MEA-O ₂ bleach is carried out, in particular lignin being separated off. The separated lignin filtrate is passed through the lignin derivative 9 to the separator 8th returned and for those in the separator 8th carried out carried out pulp washing.

After MEA / O ₂ bleaching in the delignification unit 10 The bleached pulp is sent via a pulp feed line 6.3 the bleaching unit 13 fed. The bleaching unit 13 further includes a bleach feed 13.1 , whereby bleach, for example O / P, O ₃ , P, ClO ₂ and / or FAS, can be fed. The bleaching process in the bleaching unit 13 may include elemental chloride free (ECF) or totally chlorine free (TCF) sequences. The pulp becomes in the bleaching unit 13 lightened to higher white sizes. Further, the bleaching unit becomes 13 over a third water pipe 5.5 Water from the water tank 5 fed so that the pulp in the bleaching unit 13 is washed. The bleach filtrate is separated from the pulp and a Filtratableitung 14 dissipated. The recovered pulp is via a pulp discharge 6.4 from the bleaching unit 13 derived.

The in the separator 8th separated and via the Ablaugeableitung 7.1 the distillation device 11 supplied waste liquor is in the distillation apparatus 11 further separated. By the separation or distillation in the distillation device 11 a recovery of water and MEA is achieved. The recovered water or sewage is via a sewer 5.3 the water tank 5 supplied and is the process for the recovery of pulp again available. The recovery of the MEA takes place analogously, with the MEA via an MEA feed line 4.1 the MEA container 4 is supplied. The MEA container 4 further includes an MEA Introduction 4.4 , via which the MEA can be externally supplied or refilled. This may be useful if MEA losses occur during the extraction process. The distillation device 11 further includes a solids discharge 12 , over which after the water and MEA separation leftover Ablaugesubstanzen, in particular dry Ablaugesubstanzen be removed.

Example 2 (influence of temperature in MEA digestion of wheat straw)

The essential prerequisite for a reduction in MEA decomposition during digestion is the lowering of the cooking temperature. Therefore, the digestion temperature was varied between 165 ° C and 130 ° C. The conditions and results otherwise used are listed in Table 1. For comparison, soda and soda / anthraquinone (AQ) digests were used, which are the standard method for straw digestion on an industrial scale. It was found that a lowering of the digestion temperature up to 150 ° C (WS 10, WS 3-5) is possible without the delignification performance of the system decreases (kappa number) and the yields are at a high level. Compared to conventional soda or soda / AQ outcrops, they are up to 12% higher in raw material, which means about a quarter more pulp production from the same amount of raw material. The MEA pulps had very low levels of whiteness compared to soda (15% ISO to 28% ISO). A pretreatment of the digestion material with ammonia did not bring any advantages here (WS7-WS9). Table 1 (digestion of wheat straw in the 15 liter MK cooker) test number WS1 WS2 WS10 WS3 WS4 pulping process soda Soda / AQ MEA MEA MEA code Soda 1 Soda / AQ 1 MEA5 MEA1 MEA2 amount used G 400 400 400 400 400 solid fuel % 90.3 90.3 90.3 90.3 90.3 NaOH % 16 18 0 0 0 AQ % / 0.1 / / / MEA % / / 400 400 400 ammonia % / / / / / Liquor ratio * / 4 4 4 4 4 heating up min 60 60 60 60 60 temperature ° C 160 160 165 160 155 Cooking time at Tmax min 60 100 90 90 150 Final pH value / 12.2 12.1 / / / total yield % 46.5 48 56.6 57.1 56.4 accept fraction % 42.6 46.3 54.1 53.6 53.3 splinter % 3.9 1.7 2.5 3.5 3.1 viscosity g / ml 877 906 1020 1002 991 whiteness % ISO 28 28.2 14.7 16 16.4 Kappa number / 14.6 12.1 16.7 17.4 17.3 (Continued from Table 1) WS5 WS6 WS7 WS8 WS9 WS11 MEA MEA A-MEA A-MEA A-MEA MEA MEA3 MEA4 AMEA1 AMEA2 AMEA3 MEA6 400 400 400 400 400 400 90.3 90.3 90.3 90.3 90.3 90.3 0 0 0 0 0 0 / / / / / / 400 400 400 400 400 400 / / 10 10 10 / 4 4 4 4 4 4 60 60 60 60 60 60 150 150 150 140 130 150 240 150 150 150 240 90 / / / / / / 56.8 58.9 57.6 58.4 64 57.6 54 54.3 53 55.3 52.8 56.3 2.8 4.6 4.6 3.1 *** 11.2 1.3 *** 991 948 909 863 818 / 15.5 15.5 19 16.8 15 / 17.1 18.7 18.7 21.8 24.8 /

Remarks:

• * MEA digestions = MEA / straw ratio, Add 250 ml of water for lossless flushing of the MEA, actual fleet ratio: 4.77
• ** A-MEA: with ammonia pretreatment: 10% / atro straw, liquor 3: 1, 33 min heating time to 120 ° C, 10 min at 120 ° C, then exhaust gases
• *** Cooked food was also added before serving Pulper with an Ultra-Turrax pitched (preliminary test for MEA balancing), therefore less splinters and higher acceptances

Example 3 (replacement of a part of the MEA in the digestion by water)

In order to further reduce the specific MEA consumption in the digestion stepwise MEA was replaced by water. The results are summarized in Table 2 below. A reduction of the MEA fraction in the digestion solution to 50% had hardly any negative influence on the digestion. The kappa number increased under otherwise constant conditions only by 2.5 units (WS6, WS16, 17). When the MEA content of the digestion solution was reduced to 37.5%, the kappa number increased by one more unit (WS23), while at 25% MEA fraction it jumped by 16 units, which was not sufficient for defibration digested straw portion in the form of splinters (WS18). Based on these results, standard cookages with MEA-H ₂ O ratios of 50:50 were used. Table 2 test number WS6 WS16 WS17 WS18 WS19 WS20 WS21 WS22 WS23 WS24 pulping process MEA W-MEA W-MEA W-MEA W-MEA W-MEA W-MEA W-MEA W-MEA MEA code MEA4 MEAS1 MEAS2 MEAS3 MEAS4 MEAS5 MEAS6 MEAS7 MEAS8 MEAS9 Amount used (gr) 400 400 400 400 400 400 400 400 400 400 Solid (%) 90.3 90.3 90.3 90.3 90.3 90.3 90.3 90.3 90.3 90.3 AQ (%) / / / / 0.1 0.1 0.1 / / 0.1 MEA (%) 100 75 50 25 50 25 37.5 50 37.5 100 Water (%) / 25 50 75 50 75 62.5 50 62.5 / DMAP (%) / / / / / / / 0.1 / / Liquor ratio * 4 4 4 4 4 4 4 4 4 4 Heating time (min) 60 60 60 60 60 60 60 60 60 60 temperature 150 150 150 150 150 150 150 150 150 150 Cooking time at Tmax (min) 150 150 150 150 150 150 150 150 150 150 Total yield (%) 58.9 57.6 59.7 62.6 57.7 61.5 56.8 56.9 58.6 53.5 Acceptance share (%) 54.3 54.8 56 52 56 56.2 54.9 54.1 54.7 52 Sliver (%) 4.6 2.8 3.7 10.6 1.7 5.35 1.9 2.8 3.9 1.5 Viscosity (mg / l) 948 Whiteness (ISO%) 15.5 12.4 14.8 10.6 15.7 10.2 15.1 14.8 14.5 15.5 Kappa number 18.7 19.5 22.2 39 15.7 29.4 19.5 18.3 23.6 14.6 (Continued from Table 2 :) WS25 WS26 WS27 WS28 WS29 WS30 WS31 WS32 WS33 WS34 W-MEA WOMEA WOMEA W-MEA MEA W-MEA W-MEA W-MEA W-MEA W-MEA MEAS10 MEAS11 MEAS12 MEAS13 MEAS14 MEAS15 MEAS16 MEAS17 * MEAS18 * MEAS19 * 400 400 400 400 400 400 400 400 400 400 90.3 90.3 90.3 90.3 90.3 90.3 90.3 90.3 90.3 90.3 0.05 0.1 0.1 / / / 0.1 0.1 0.1 0.1 50 37.5 37.5 37.5 100 50 50 50 50 50 50 62.5 62.5 62.5 / 50 50 50 50 50 / / / 0.1 0.1 0.1 0.1 / / / 4 4 4 4 4 4 4 4 4 4 60 60 60 60 60 60 60 60 60 60 150 150 150 150 150 150 150 150 150 150 150 150 150 150 150 150 150 150 150 150 56.7 55.3 55.2 57 52.8 56.9 57 56.9 56.4 56.7 56.6 average 54.6 53.6 51.6 53 50.4 53.3 55 55 54.5 55 54.8 2.1 1.7 3.6 4 2.4 3.6 2 1.9 1.9 1.7 1.8 14.4 15.3 14.8 13.3 13.3 14.2 14.5 14.4 16.6 17.8 18.5 23.8 18 20 17.3 17.1 17.5

Remarks:

• W = water
• O = oxygen
• In MEAS 11 use of oxygen after cooking or at the cooling phase
• In MEAS 12 use of oxygen one hour before the end of cooking
• * Pouring bleach

Example 4 (Use of catalysts in the digestion system MEA-H ₂ O)

Since the MEA digestion takes place under alkaline conditions and in known alkaline digestion processes, such as the soda and the Kraft process, AQ as a catalyst for accelerating the digestion and for stabilizing the carbohydrates against degradation of. Chain end is used, this catalyst was also used in MEA digestion. Quantities of 0.05-0.1% / raw material accelerate the digestion significantly. The kappa number is additionally reduced by 4-5 units (WS19-21, WS24, 25). This makes it possible to achieve the same delignification with an MEA / H ₂ O ratio of 37.5: 62.5 as in a pure MEA digestion. In contrast, the use of DMAP (4-dimethylaminophenol hydrochloride) as catalyst did not affect the digestion (WS22; WS28-31).

Example 5 (Use of MEA as alkali source in the oxygen delignification of MEA pulps)

To activate oxygen in the further delignification of pulps, NaOH is usually used as the alkali source. It was investigated whether MEA can substitute NaOH as an alkali source as it is beneficial for the closure of the pulp manufacturing process when in the cooking and the oxygen delignification the same base is used. Table 3 summarizes oxygen delignification results using both NaOH and MEA as the alkali source. The NaOH amount was 2 and 3% while 10-160% MEA / pulp was used. The reaction temperature was varied between 90 and 110 ° C, while the reaction time was kept constant at 90 min.

With a Ausgangsskappazahl in the unbleached pulp of 19.5 this could be lowered depending on temperature and amount of alkali up to half. Here, MEA proved to be very effective, however, with 20% MEA / pulp being needed to reach a kappa number of 10.9 at 90 ° C, which is suitable for further bleaching of the pulp (high O stage). The resulting bleach liquor can be separated in a wash and used to wash the Kocherstoffes. It can then be worked up together with the digestion solution (chemical recovery). Table 3 NaOH (%) MEA deployment (%) Temp. Time (min) Kappa number Whiteness (% ISO) Delignification degree (%) MEAS6 / / / / 19.5 15.1 / MEAS6-O1 / 10 90 90 13 18.7 33.3 MEAS6-O2 / 20 90 90 12.3 19.8 37 MEAS6-O3 / 40 90 90 11.5 20.1 41 MEAS6-O4 / 80 90 90 10.8 23 44.6 MEAS6-O5 / 120 90 90 10.8 26.05 44.6 MEAS6-O6 / 160 90 90 9.5 26.3 51.3 MEAS6-O7 2 / 90 90 10.6 24.6 45.6 MEAS6-O8 3 / 90 90 9.5 26.9 51.3 MEAS6-O9 / 10 100 90 12.6 22 35.4 MEAS6-O10 / 20 100 90 11.6 24.4 40.5 MEAS6-O11 / 40 100 90 10.8 26.9 44.6 MEAS6-O12 / 80 100 90 10.6 28.6 45.6 MEAS6-O13 / 120 100 90 10.7 28.6 45.1 MEAS6-O14 / 160 100 90 10.5 28.6 46.1 MEAS6-O15 2 / 100 90 9.7 28.2 50.2 MEAS6-O16 3 / 100 90 9.4 31.1 51.8 MEAS6-O17 / 10 110 90 10.2 24.8 47.7 MEAS6-O18 / 40 110 90 10.2 27.2 47.7 MEAS6-O19 / 160 110 90 10.5 25.3 46.1 MEAS6-O20 3 / 110 90 8.1 35.3 58.5 MEAS4 / / / / 16 15.7 / MEAS4-O21 / 20 90 90 9.5 24.3 40.6 MEAS4-O22 / 80 90 90 9.4 27.2 41.2 MEAS4-O23 / 160 90 90 9 27.7 43.7 MEAS4-O24 2 / 90 90 8.7 27.3 45.6 Cooking for the bleach / / / / 17.2 14.4 / Great O level / 20 90 90 10.9 21.3 36.6

Remarks:

• In all O experiments consistency 20%, O-pressure 6 bar, yield after O level: 97.2%

Example 6 (Bleaching of MEA pulps)

Of the pulp delignified with oxygen and having a kappa number of 10.9 was used in a completely chlorine-free bleaching sequence (TCF) and a bleaching sequence using small amounts of chlorine dioxide (D) bleached. Each bleaching stage has been optimized and the optimized ones Conditions in the overall sequence for bleaching a larger one Pulp amount to determine the papermaking properties used the pulps.

To the oxygen level became the substance in a complexing agent stage (Q) treated to remove heavy metals. There were different Complexing agent or complexing agent combinations used (see Table 4). To improve the solubility of heavy metals the substance was mixed with sulfuric acid at between pH 4 and 2.5, after 30 min treatment at 60 ° C. the removal of the complexed metals took place in a wash. Subsequently, the substances were in a peroxide-reinforced Oxygen stage (OP) and alternatively bleached only with peroxide. The Conditions of these stages have been varied to optimum conditions to find (see Table 4). The results show that a stronger Lowering the pH in the Q-stage the effectiveness of the following Improved bleaching stage. Regarding the bleaching effect was consider the OP level of the P-stage taking into account the peroxide use. For this reason, the OP stage became the further bleaching sequences used.

As already mentioned were in the final bleaching of the pulps both chlorine dioxide (D) and ozone (Z) are used (see Table 5). In these steps, complexing agents were added again to the ozone stage and the final peroxide stage (P) more selective to design.

The chlorine dioxide level was further optimized with regard to the use of chemicals, and an amount of 0.2% chlorine dioxide / cellulose was determined for the bleaching of the large batch. In the ozone treatment a constant 0.35% ozone was used. For both bleaching variants, a peroxide stage was finally used, which was further optimized with regard to the use of chemicals. In the final bleaching of the large batches, 2% H ₂ O ₂ and 2% NaOH were used.

The final whiteness reached in the sequence O-OP- (DQ) -P was 79.8% ISO while in the sequence O-OP- (ZQ) -P a whiteness of 80.1% ISO was achieved (Table 5). This is a sufficient degree of whiteness for most uses of straw pulp. Table 4 NaOH (%) H ₂ O ₂ (%) DTPA (%) DTPMPA (%) MgSO ₄ (%) Na ₂ SiO ₃ (%) T (° C) Time (min) Kappa number whiteness Residual H ₂ O ₂ Degree of Delegnif. (%) O / / / / / / / / 10.9 21.3 / / Q * / / 0.2 / / / 60 30 10.9 28.1 / / OP1 2.5 4 / 0.05 0.1 / 98 90 5.8 51.6 0 46.8 OP2 2.5 4 / 0.05 0.1 2 98 90 4.8 62.5 0 56 OP3 2.5 4 / 0.05 0.1 2 98 90 4.6 63.5 0 57.8 OP4 2 3 / 0.05 0.1 2 98 90 5 61.2 0 54.1 Q ** / / 0.2 / / / 60 30 10.9 29.8 / / OP5 2 1 / / / 2 98 90 5.6 53.3 0 48.6 OP6 2 1.5 / / / 2 98 90 5 59.3 0 54.1 OP7 2 2 / / / 2 98 90 4.7 60.4 0 56.9 OP8 2 2.5 / / / 2 98 90 4.7 63 0 59.9 OP-Gross 2 1.5 / / / 2 98 90 4.8 56 0 56 Q *** / / 0.2 / / / 60 30 4.8 57 / / P1 1.5 1 / / / 2 80 240 3.4 50.5 0 29.2 P2 1.75 2 / / / 2 80 240 3.3 50.2 0 31.2 P3 2 3 / / / 2 80 240 3.2 49.3 0 33.3 P4 2.25 4 / / / 2 80 240 3.2 55 0 33.3 P5 1.5 1 / / / 3 80 120 3.3 54.1 0 31.2 P6 1.75 2 / / / 3 80 120 3.2 55.6 0 33.3 P7 2 3 / / / 3 80 120 3.2 57.6 0 33.3 P8 2.25 4 / / / 3 80 120 3.2 58.8 0 33.3 P9 1.5 1 / / / 3 70 120 3.3 55.6 0 31.2 P10 1.75 2 / / / 3 70 120 3.3 56.2 0 31.2 P11 2 3 / / / 3 70 120 3.2 55.4 0 33.3 P12 2.25 4 / / / 3 70 120 3.2 57.7 0 33.3

Remarks:

• Q *: pH beginning 4 - pH end 4,5
• Q **: pH beginning 2.8 - end 3.2
• Q ***: pH beginning 2.5 - pH end 3

Table 5 ClO ₂ (%) Ozone (%) NaOH (%) H ₂ O ₂ (%) DTP A (%) DTPM PA (%) Mg SO ₄ (%) Na ₂ SiO ₃ (%) T (° C) Time (min) Kappa number whiteness Residual H ₂ O ₂ (%) Degree of Delegnif. (%) operating room / / 2 1.5 / / / 2 98 90 4.8 56 / 56 D (Q) 1 0.2 / / / 0.2 / / / 70 120 3.2 66.5 / 33.3 D (Q) 2 0.4 / / / 0.2 / / / 70 120 3 67.2 / 37.5 D (Q) 3 0.6 / / / 0.2 / / / 70 120 2.7 68.4 / 43.7 D (Q) large 0.2 / / / 0.2 70 120 3.3 69.8 / 31.2 D (Q) P1 / / 1.5 2 / / / 2 70 30 3 70.9 99.1 6.2 D (Q) P2 / / 1.5 2 / / / 2 70 30 2.7 71.5 99.6 10 D (Q) P3 / / 1.5 2 / / / 2 70 30 2.4 73.8 99.2 11.1 Dg (Q) P1 / / 2 2 / / / 3 70 120 2.7 78.7 98.9 18.2 Dg (Q) P2 / / 2.5 4 / / / 3 80 240 2.5 80.9 40.2 24.2 Dg (Q) P3 / / 2 2 / / / 3 80 240 2.7 79.7 66.6 18.2 Dg (Q) P4 / / 2.25 3 / / / 3 80 240 2.6 80.1 62.8 21.2 Dg (Q) P5 / / 2.5 4 / / 0.2 / 80 240 2.7 80.2 41.3 18.2 Dg (Q) Pgross / / 2 2 / / 0.2 / 80 240 2.7 79.8 42.2 18.2 Z (Q) large / 0.35 / / 0.2 / / / 50 9.59 1.2 78.62 / 75 Z (Q) P1 / / 1 0.5 / / 0.2 / 70 120 0.9 78.7 88 25 Z (Q) P2 / / 1.2 1 / / 0.2 / 70 120 0.8 78.9 74 33.3 Z (Q) P3 / / 2 2 / / 0.2 / 80 120 0.8 81.4 67 33.3 Z (Q) Pgross / / 2 2 / / 0.2 / 80 120 0.8 80.5 89.8 33.3

Example 7 (Technological properties of MEA pulps)

The Tables 6 to 8 contain technological and optical values of a unbleached and of the same pulp, which in the two different Sequences was bleached. The values determined are for wheat straw pulps very good, especially considering the high yields of the pulps considered. The strength values increase after bleaching even on what pulps, in conventional Procedures are produced, not the case. This is likely also on the gentle digestion conditions of the MEA process be due. The bleaching reduces something the high hemicellulose content of MEA pulps, which is positive affects the strengths.

Comparisons between wheat straw pulps produced in the MEA process and in the conventional soda / AQ process have shown that MEA pulps are technologically superior to the corresponding soda pulps. Table 6 raw material wheat straw Chemical use 200% Yield: 56.6% Accepted stock: 54.80% digestion: MEA Kappa number: 17.2 / Whiteness of the bleached fabric init. 14.4% ISO Viscosity: WS 32-34; MEAS 17-19 1. Grinding degree 2. Grinding degree 3. Grinding degree 4. Grinding degree 5. Grinding degree 6. Grinding degree freeness freeness freeness freeness ° SR 33 42.5 47.5 55.5 40 45 50 Grinding degree CSF ml 383 279 235 177 304 256 216 grinding time min 0 1 2 5 1 2 3 Specific volume cm ³ / g 2.2 2.22 1.89 1.8 2.22 2.06 1.86 breaking length km 6.23 6.84 7.23 7.55 6.68 7.04 7.33 Burst pressure kPa 226 272 288 310 260 280 295 Bursting pressure 80 g / m ² kPa 244 299 315 341 285 307 323 Druckreißfestk. cN 24.9 24 22.7 22.7 24 23 23 Druckreißfestk. 100 g / m ² cN 33.6 32.9 31.2 31.3 33 32 31 folding endurance strength value 4.6 4.7 4.7 4.9 4.7 4.7 4.8 Tensile index Nm / g 61.2 67.1 70.9 74.1 65.5 69 71.9 Tear Index mN · m ² / g 3.4 3.3 3.1 3.1 3.3 3.2 3.1 Burst index kPa · m ² / g 3.1 3.7 3.9 4.3 3.6 3.8 4.0 Absorptionsk. m ² / kg 12.06 11.01 10.23 10.39 11.29 10.62 10.28 Opacity 80 g / m ² % 98.9 98.3 97.6 97.5 98.5 98 97.6 LSK m ² / kg 24.6 21.6 19.2 18.7 22.4 20.4 19.0 Whiteness at RK sheet % ISO 24.6 23.4 22.9 22.2 porosity ml / min 52 33 31 28 roughness ml / min 2336 3566 3000 2829 Gurley sec 230 330 356 418

Remarks:

• Paper wheat straw MEA32-34 unbleached (15/10/2008)
• 150 ° C, 150 min, starting material for bleaching tests
• Substance name WS 32-34; MEAS 17-19

Table 7 raw material wheat straw Chemicals. 200% Yield: 56.6% Bleach OQ (OP) ZP digestion: MEA Kappa number: 0.8 / Whiteness of the blended fabric 14,4% ISO Shared flat, gebl. 80.5 WS 32-34; MEAS 17-19 1. Grinding degree 2. Grinding degree 3. Grinding degree 4. Grinding degree 5. Grinding degree 6. Grinding degree freeness freeness freeness freeness ° SR 32 42.5 46.5 53.5 40 45 50 Grinding degree CSF ml 396 279 244 190 304 256 216 grinding time min 0 1 2 5 1 2 4 Specific volume cm ³ / g 2.2 1.91 1.82 1.65 1.98 1.85 1.73 breaking length km 6.26 7.31 7.4 7.93 7.06 7.37 7.66 Burst pressure kPa 290 345 347 351 332 346 349 Bursting pressure 80 g / m ² kPa 292 341 350 358 329 347 354 Druckreißfestk. cN 28.8 28.5 26.8 24.2 29 27 26 Druckreißfestk. 100 g / m ² cN 36.3 35.2 33.8 30.9 35 34 32 folding endurance strength value 4.8 5.1 5.0 5.0 5.0 5.0 5.0 Tensile index Nm / g 61.5 71.7 72.6 77.8 69.3 72.3 75.2 Tear Index mN · m ² / g 3.6 3.5 3.4 3.1 3.5 3.4 3.2 Burst index kPa · m ² / g 3.7 4.3 4.4 4.5 4.1 4.3 4.4 Absorptionsk. m ² / kg 0.25 0.26 0.29 0.48 0.26 0.28 0.38 Opacity 80 g / m ² % 74.8 71.6 69.6 69 72.3 70.3 69.3 LSK m2 / kg 24.4 20.1 18.5 15.5 21.1 19.1 17.0 Whiteness at RK sheet % ISO 81.7 80 78.1 71.5 porosity ml / min 64 45 37 20 roughness ml / min 1823 2416 2983 3019 Gurley sec 179 307 382 612

Remarks:

• Wheat straw MEA32-34 OQ (OP) (ZQ) P-1 (15.10.2008)
• 150 ° C, 150 min, bleached
• Substance name WS 32-34; MEAS 17-19

Table 8 raw material wheat straw Chemical use 200% Yield: 56.6% Bleach OQ (OP) DP digestion: MEA Kappa number: 2.7 / Whiteness of the blended fabric 14,4% ISO Shared flat, gebl. 79.8 WS 32-34; MEAS 17-19 1. Grinding degree 2. Grinding degree 3. Grinding degree 4. Grinding degree 5. Grinding degree 6. Grinding degree freeness freeness freeness freeness ° SR 34.5 45 48.5 55 40 45 50 Grinding degree CSF ml 364 256 227 180 304 256 216 grinding time min 0 1 2 5 1 1 3 Specific volume cm ³ / g 1.98 1.79 1.78 1.69 1.88 1.79 1.76 breaking length km 6.41 7.27 7.48 8.02 6.86 7.27 7.61 Burst pressure kPa 290 339 346 357 315 339 349 Bursting pressure 80 g / m ² kPa 300 343 357 369 323 343 360 Druckreißfestk. cN 28 28.1 26.4 24.2 28 28 26 Druckreißfestk. 100 g / m ² cN 36.2 35.6 34 31.2 36 36 33 folding endurance strength value 4.8 5.1 5.0 5.0 5.0 5.1 5.0 Tensile index Nm / g 62.9 71.3 73.4 78.6 67.3 71.3 74.6 Tear Index mN · sm ² / q 3.6 3.6 3.4 3.1 3.6 3.6 3.3 Kurst Index kPa · m ² / g 3.8 4.3 4.5 4.6 4 4.3 4.5 Absorptionsk. m ² / kg 0.3 0.32 0.32 0.48 0.31 0.32 0.36 Opacity 80 g / m ² % 75 72.7 70.8 69 73.8 72.7 70.4 LSK m ² / kg 23.3 20.6 18.8 15.6 21.9 20.6 18.1 Whiteness at RK sheet % ISO 78.6 76.8 76.7 71.5 porosity ml / min 43 25 22 18 roughness ml / min 1095 1410 1320 2461 Gurley sec 264 471 574 745

Remarks:

• Wheat straw MEA32-34 OQ (OP) (DQ) P (15.10.2008)
• 150 ° C, 150 min, bleached
• Substance name WS 32-34; MEAS 17-19

Example 8 (elemental analysis of the digest dissolved waste liquors after recovery of the MEA)

The use of low-boiling organic solvents for pulp production made possible light the separation of the solvent and the gone into solution components of digestion by distillation. While the solvent is being reused, a use has to be found for the solutes. In conventional processes, this is the energetic use associated with the recovery of the inorganic digestion chemicals.

In MEA digestion, in addition to the combustion of the concentrated waste liquor substance after distilling off the MEA, the use of the dissolved lignocelluloses as a chemical raw material is also conceivable or as an organic fertilizer with a long-term effect. The latter utilization requires the highest possible nitrogen content. This nitrogen, unlike inorganically bound nitrogen, is slowly released to the soil by microbial decomposition of the substrate. Lignocelluloses also have a high water absorption and water binding capacity and increase the pore volume of soils. As shown in Table 9, approximately 6% organically bound nitrogen was detected in MEA-free waste liquors. Table 9 (elemental analysis) ThermoQuest EA 1112 substance analysis date Nitrogen (%) Carbon (%) Hydrogen (%) Oxygen (%) reading Average reading Average reading Average MW Wheat straw 016 wheat straw 017 08/11/2008 08/11/2008 0.46 0.44 0.45 41.83 41.93 41.88 5.66 5.57 5.61 52.05 MB1 residue 1 p2 034 MB1 residue 1 p2 035 08/11/2008 08/11/2008 5.98 6.07 6.02 47.16 47.75 47.45 6,39 6,50 6.44 40.08 MB1 residue 2 p2 036 MB1 residue 2 p2 037 08/11/2008 08/11/2008 6,91 6,93 6.92 45.34 45.86 45.6 6,79 6,77 6.78 40.7

• *) something inhomogeneous
• **) inhomogeneous
• ***) very inhomogeneous

1

biomass supply

2

Stove

3

catalyst supply line

4

MEA container

4.1

MEA supply

4.2

first MEA feedback

4.3

second MEA feedback

4.4

MEA Introduction

5

water tank

5.1

first water pipe

5.2

second water pipe

5.3

sewer

5.4

Kocher supply

5.5

third water pipe

6.1

Biomass digestion line

6.2

Pulp forwarding

6.3

Pulp supply

6.4

Pulp discharge

7.1

Ablaugeableitung

8th

separator

9

Ligninableitung

10

Delignifizierungseinheit

10.1

oxygen supply

11

distillation device

12

Solids discharge

13

bleaching unit

13.1

Bleach supply

14

filtrate discharge

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 4597830 A [0008]
• - US 4178861 A [0008]
• EP 0149753 B [0008]
• - DE 2640027 A [0008]

Cited non-patent literature

• - Harlow, WM, Wise, LE, Am. J. Botany 25 (1938): pp. 217-219 [0004]
• - Wallis, Cellulose Chemistry and Technology, 10 (3) (1976), pp. 345-355 [0004]

Claims (26)

A process for obtaining pulp by separating lignin from a lignocellulosic biomass in the form of plants or plant parts, wherein the lignocellulose-containing biomass in an alkaline medium containing alkanolamine, digested in a digester and separated lignin from the resulting raw pulp characterized in that the lignocellulosic biomass is not derived from wood and is digested at a temperature of less than about 170 ° C in an alkanolamine and water based disintegrant in which the weight ratio of alkanolamine to water is 80:20 to 20:80 is set, and resulting raw pulp is separated from the waste liquor by conventional methods. Method according to claim 1, characterized in that that the lignocellulosic biomass is annual is. Method according to claim 1 or 2, characterized that as lignocellulosic biomass grain straw, in particular Wheat straw, being treated. Method according to one of claims 1 to 3, characterized in that the alkanolamine is a short-chain Alkanolamine, in particular an alkanolamine having 1 to 4 carbon atoms is used. Method according to claim 4, characterized in that that as alkanolamine monoethanolamine, monopropanolamine and / or Monobutanolamine, especially monoethanolamine, can be used. Method according to at least one of the preceding Claims, characterized in that the ratio of alkanolamine to water at 70:30 to 30:70, especially at 60:40 to 40:60 is set. Method according to Claim 6, characterized that the ratio of alkanolamine to water is 53:57 is set to 57:53. Method according to at least one of the preceding Claims, characterized in that the digestion temperature less than about 165 ° C, in particular less than 150 ° C is set. Method according to at least one of the preceding Claims, characterized in that the digestion temperature to more than about 120 ° C, especially more than about 140 ° C is set. Method according to claim 8 or 9, characterized that the digestion temperature is set to 140 to 160 ° C. becomes. Method according to at least one of the preceding Claims, characterized in that the digestion after heating for a period of 15 min. to 4 h, in particular from 1 h to 3 h is performed. Method according to claim 11, characterized in that that digestion for a period of 2 to 3 h is performed. Method according to at least one of the preceding Claims, characterized in that the liquor ratio of biomass to be digested (dry substance) and digesting agent Alkanolamine / water to about 8: 1 to 2: 1, especially about 5: 1 to 3: 1, is set. Method according to at least one of the preceding Claims, characterized in that the digestion is carried out continuously in the digester. Method according to at least one of the preceding Claims, characterized in that the digestion in the presence of a catalyst, in particular in the form of a Chinon. Method according to claim 15, characterized in that that is chosen as the catalyst anthraquinone. Method according to at least one of the preceding claims, characterized in that the raw pulp from the spent liquor of the digester by solid / liquid separation, in particular filtration, pressing or Centrifuging, is separated and the resulting waste liquor filtrate, optionally after evaporation, enriched in alkanolamine and returned to the digester. Method according to claim 17, characterized in that that washed the resulting raw pulp and the resulting wash liquor is brought together with the cooking liquor. Method according to at least one of the preceding Claims, characterized in that the raw pulp, separated from the cooking liquor and optionally washed, bleached becomes. Method according to claim 19, characterized that the bleaching is carried out as part of an alkanolamine / oxygen stage, with alkanolamine as alkali source, for further delignification carried out, the bleached pulp from adherent separated from liquid fractions which still contain alkanolamine, in particular pressed or filtered to the alkanolamine enriched liquid phase, especially the filtrate, to feed back to the stove. Method according to at least one of the preceding Claims, characterized in that evaporation, optionally carried out at different process steps is done with low thermal stress, especially in a thin film evaporator, falling film evaporator or tube evaporator. Method according to at least one of the preceding Claims, characterized in that the delignification is repeated in a cooker. Method according to at least one of the claims 19 to 22, characterized in that the filtrate, after the Measure of bleaching has been obtained as a washing solution for washing the unbleached raw pulp. Method according to at least one of the preceding Claims, characterized in that the raw pulp or after bleaching with the alkanolamine / oxygen stage obtained pulp a further bleaching in usual ECF and TCF sequences is subjected. A method according to any one of claims 19 to 24, characterized in that the bleaching, in particular the further bleaching of the pulp, by the action of oxygen / hydrogen peroxide, hydrogen peroxide in the presence of NaOH, O ₃ , ClO2 and / or formamidinesulfinic acid (FAS) is performed , Use of the according to the method according to at least one of the preceding claims obtained product, optionally after the alkanolamine recovery, in particular monoethanolamine recovery, as a paper, energy and chemical raw material or as organic N-Depot fertilizer.